Antepartum risk factors and outcomes of massive transfusion for elective cesarean section: a nationwide retrospective cohort study.

Background: Postpartum hemorrhage is one of the leading causes of maternal mortality and morbidity. The etiology of postpartum hemorrhage exhibits variations in relation to the mode of birth; consequently, risk factors for massive transfusion in elective cesarean section might diverge from those encountered in vaginal birth or emergency cesarean section. The main purpose of this study was to investigate antepartum risk factors of massive transfusion for elective cesarean section.

Methods: We conducted a retrospective cohort study based on data from a nationwide system that collected inpatient medical records from tertiary hospitals in mainland China. We included women who had undergone elective cesarean section from January 2013 to August 2018. Primary outcome was massive transfusion defined as transfusion of more than eight units of red blood cells on the day of childbirth. Candidate risk factors were identified by the 10th revision of International Classification of Diseases Codes of admission diagnoses. The relationship between each factor and massive transfusion was assessed using multivariable logistic regression.

Results: A total of 294,695 women were included and 572 of them received massive transfusion (incidence: 194 per 100,000 elective cesarean sections). Maternal age [adjusted odds ratio (aOR) 1.22; 95% confidence interval (CI) 1.10-1.48], anemia (aOR 1.66; 95% CI 1.34-2.05), thrombocytopenia (aOR 3.54; 95% CI 2.39-5.05), coagulopathy (aOR 25.92; 95% CI 8.59-69.50), hypoalbuminemia (aOR 2.97; 95% CI 1.86-4.53), hepatic dysfunction (aOR 1.65; 95% CI 1.04-2.47), uterine scar (aOR 1.39; 95% CI 1.15-1.67), multiple pregnancy (aOR 2.84; 95% CI 1.74-4.38), polyhydramnios (aOR 2.52; 95% CI 1.19-4.68) and placenta previa (aOR 25.03; 95% CI 21.04-29.77) were associated with massive blood transfusion for elective cesarean section. Among the women receiving massive blood transfusion, 7 (1.2%) died during hospitalization, 126 (22.0%) needed hysterectomy, 25 (4.4%) uterine packing and 57 (10.0%) uterine artery ligation.

Conclusions: Ten risk factors of massive transfusion were identified in women undergoing elective cesarean section. Our findings may facilitate blood products preparation and provide opportunities for applying prophylactic strategies prior to cesarean section for women at high risk of massive transfusion.